1. Field of the Invention
The present invention relates to a bonded body made from different materials, which is obtained by bonding a first joint surface of a first member containing a metallic or inorganic material to a second joint surface of a second member containing a thermoplastic resin. The present invention further relates to a method for producing the bonded body.
2. Description of the Related Art
A bonded body made from different materials (a so-called different-material-bonded body) is produced by thermally weld-bonding a member, which is composed of a thermoplastic resin, to another member which is composed of a metallic or inorganic material. By way of known technology, the thermoplastic resin having a low melting point is molten and is brought into contact with the metallic or inorganic material. Then, the thermoplastic resin is cooled and solidified to result in mutual bonding of the members.
The metallic or inorganic material has a relatively low wettability in coaction with the molten thermoplastic resin. In other words, the thermoplastic resin is likely to be repelled by the metallic or inorganic material. Therefore, it is difficult to increase the contact area between the thermoplastic resin and the metallic or inorganic material. Thus, it is difficult to increase the bonding strength of the different-material-bonded body.
However, particularly in the case of using the different-material-bonded body as a structural component, the different-material-bonded body is required to have a high bonding strength. Japanese Laid-Open Patent Publication No. 2009-255429 and Japanese Laid-Open Patent Publication No. 2010-064397 propose a method, which contains the steps of chemically etching a joint surface of a metallic material to form microscopic pores therein, introducing the molten thermoplastic resin into the microscopic pores, and cooling and solidifying the thermoplastic resin in this state. According to this method, bonding strength can be increased by a so-called anchor effect.